1. Field of the Invention
This invention relates to a detergent-softening composition. More specifically, the present invention relates to softening/anti-static compositions adapted for use in the wash cycle of a laundering operation, the composition including as essential ingredients a nonionic detergent, an anionic detergent, a cationic fabric softener-anti-static agent and a soil release promoting polymer of the polyethylene terephthalate-polyoxyethylene terephthalate (PET-POET) type.
2. Description of the Prior Art
Compositions useful for treating fabrics to improve the softness and feel characteristics thereof are known in the art.
When used in domestic laundering, the fabric softeners are typically added to the rinse water during the rinse cycle having a duration of only from about 2 to 5 minutes. Consequently, the consumer is required to monitor the laundering operation or take other precautions so that the fabric softener is added at the proper time. This requires the consumer to return to the washing machine either just prior to or at the beginning of the rinse cycle of the washing operation which is obviously burdensome to the consumer. In addition, special precaution has to be taken to use a proper amount of the fabric softener so as to avoid over dosage which may render the clothes water repellant by depositing a greasy film on the fabric surface, as well as imparting a certain degree of yellowness to the fabrics.
As a solution to the above-noted problems, it has been known to use fabric softeners which are compatible with common laundry detergents so that the softeners can be combined with the detergents in a single package for use during the wash cycle of the laundering operation. Examples of such wash cycle added fabric softening compositions are shown in U.S. Pat. Nos. 3,351,438, 3,660,286 and 3,703,480 and many others. In general, these wash cycle fabric softening compositions contain a cationic quaternary ammonium fabric softener and additional ingredients which render the softening compounds compatible with the common laundry detergents.
It is also known, however, that the cationic softening compounds added to the wash cycle, either as an ingredient in a detergent-softener composition or as a wash cycle softener, interfere with the brightening activity, as well as the cleaning efficiency of the detergent. As a result, it has been sought to offset to some degree this interference in detergent-softening compositions by using nonionic surfactants, higher levels of brightener compound, carboxymethylcellulose, anti-yellowing compounds, bluing agents and so forth. However, little improvement has been made in wash cycle softening compositions using a variety of detergents, most of which are anionics.
There have been many disclosures in the art relating to detergent compositions containing cationic softening agents, including the quaternary ammonium compound softening agents, and nonionic surface-active compounds. As representative of this art, mention can be made of U.S. Pat. Nos. 4,264,457; 4,239,659; 4,259,217; 4,222,905; 3,951,879; 3,360,470; 3,351,483; 3,644,203; etc. In addition, U.S. Pat. Nos. 3,537,993; 3,583,912; 3,983,079; 4,203,872, and 4,264,479, specifically disclose combinations of nonionic surface-active agent, cationic fabric softener and another ionic surfactant or modifier, such as zwitterionic surfactants, amphoteric surfactants, and the like.
While many of these prior art formulations provide satisfactory cleaning and/or softening under many different conditions they still suffer from the defects of not providing adequate softening--e.g. comparable to rinse cycle--added softeners.
U.S. Pat. No. 3,920,565 discloses a liquid rinse cycle fabric softener composition containing 2 to 15% of a cationic fabric softener and 0.5 to 4.0% of an alkali metal salt of a fatty acid of from 16 to 22 carbon atoms (soap) and optionally, up to 2% of a nonionic emulsifier, the balance water. The di-higher alkyl dimethyl ammonium chlorides are the preferred cationics, although mono-higher alkyl quats are also mentioned.
It is generally accepted in the art that the mono-higher alkyl quaternary ammonium compounds, such as, for example, stearyltrimethyl ammonium chloride, being relatively water-soluble, are less effective softeners that the di-higher alkyl cationic quaternary softeners (see, for example, U.S. Pat. No. 4,326,965), and, therefore, their use in conjunction with, for example, anionic detergents, such as fatty acid soaps, with which they are capable of forming softening complexes has been suggested for use as rinse cycle fabric softeners.
The present inventor previously discovered that stable, fabric softening compositions having improved dispersibility in cold water as used in the rinse cycle, are provided by a cationic quaternary ammonium compound, as the sole softener, and an anionic sulfonate at a weight ratio of cationic to anionic of from about 80:1 to 3:1 (see U.S. Pat. No. 3,997,453). This patent discloses both mono-higher and di-higher alkyl cationic quaternary softening compounds and also discloses alkyl benzene sulfonates as the anionic compound. According to this patent, the addition of minor amounts of the anionic sulfonate to water dispersions of the excess amount of quaternary softener reduces the viscosity of the dispersion and produces a homogeneous liquid which is readily dispersible in cold water (i.e. the rinse cycle of an automatic washing machine).
As mentioned above, however, it has been recognized for some time that it would be highly desirable as a matter of convenience to employ the fabric softening formulation concurrently with the detergent in the wash cycle of the washing machine.
U.S. Pat. No. 4,222,905 to Cockrell, Jr. discloses laundry detergent compositions which may be in liquid form and which are formulated from certain nonionic surfactants and certain cationic surfactants, including mono-higher alkyl quaternary ammonium compounds, such as tallowalkyltrimethyl ammonium halide, at a nonionic:cationic weight ratio of from 5:1 to about 1:1. This patent teaches that the amount of anion-producing materials should be minimized and preferably totally avoided, but in any case, anionic materials having a dissociation constant of less than 1.times.10.sup.-5, such as sodium C.sub.11.8 linear alkylbenzene sulfonate, should be contained only in amounts up to 10%, by weight, of the cationic surfactant.
Nonionic/cationic mixed surfactant detergent compositions having a nonionic:cationic weight ratio of from about 1:1 to 40:1 in which the nonionic surfactant is of the class having a hydrophilic-lipophilic balance (HLB) of from about 5 to about 17, and the cationic surfactant is of the class of mono-higher alkyl quaternary ammonium compounds in which the higher alkyl has from about 20 to about 30 carbon atoms, are disclosed by Murphy in U.S. Pat. No. 4,239,659. This patent provides a general disclosure that other adjunct components may be included in their conventional art-established levels for use which is stated to be from about 0 to about 40%. A broad list of adjunct components is given including semi-polar nonionic, anionic, zwitterionic and ampholytic cosurfactants, builders, dyes, fillers, enzymes, bleaches, and many others. There are no examples using, and no disclosure of, anionic surfactants, however, it is stated that the cosurfactants must be compatible with the nonionic and cationic and can be any of the anionics disclosed in U.S. Pat. No. 4,259,217 to Murphy.
This latter Murphy patent discloses surfactant mixtures of nonionic surfactants having an HLB of from about 5 to about 17 and a cationic surfactant, inclusive of mono-higher alkyl quaternary ammonium compounds, at a nonionic:cationic weight ratio of from 5.1:1 to about 100:1. According to this patent, the detergent compositions may contain up to about 50%, preferably from about 1 to about 15%, of anionic surfactants and/or zwitterionic surfactants. The anionic surfactants include, among others, linear alkyl benzene sulfonates and alkyl ether sulfates. Example XV in column 40 of this patent describes a heavy duty liquid laundry detergent composition of the following formula:
______________________________________ Component Weight ______________________________________ Sodium sulfate of C.sub.12-15 alcohol 5.0 ethoxylated with 3 moles of ethylene oxide C.sub.12-13 alcohol ethoxylate containing an 20.0 average of 6.5 moles ethylene oxide Coconutalkyltrimethyl ammonium chloride 3.5 Glycine 8.0 Sodium toluene sulfonate 10.0 Water and minors Balance to 100. ______________________________________
The following heavy duty liquid detergent composition is shown in Example XVII (column 41):
______________________________________ Component Weight ______________________________________ Condensate of C.sub.14-15 fatty alcohol with 28.5 an average of 7 moles of ethylene oxide Triethanolamine salt of linear alkylbenzene 20.0 sulfonic acid wherein the alkyl chain has an average of 11.9 carbon atoms C.sub.8-18 alkyldihydroxyethyl methyl ammonium 1.5 chloride Ethanol 10.0 Diethylenetriamine pentamethyl phosphonic 0.3 acid Citric acid 0.2 9.1 mixture of dimethylpolysiloxane and 0.3 acrogel silica emulsified in highly ethoxylated fatty acid (commercially available from Dow Corning as DB31) Saturated fatty acid having from 16 to 22 0.75 carbon atoms in the alkyl chain Proteolytic enzyme 0.4 Minor adjuvants and water Balance to 100. ______________________________________
A liquid laundry detergent and fabric softener composition which contains about 3-35% by weight of a nonionic surfactant, about 3-30% by weight mono-higher alkyl quaternary ammonium compound cationic surfactant and a mixture of anionic surfactants including (a) C.sub.4 -C.sub.10 alcohol sulfates and (b) C.sub.12 -C.sub.22 alcohol ethoxylated ether sulfates or carboxylates is disclosed in U.S. Pat. No. 4,264,457 to Beeks and Wysocki. The mole ratio of total cationic surfactant to total anionic surfactant can vary from 0.8:1 to 10:1. According to the patentees, the selection of and proportions of the two specific anionic surfactants to the exclusion of other known anionic surfactants is essential to obtain the maximal effectiveness for detergency, softness and anti-static properties.
The present inventor has also previously discovered that softening and anti-static performance of a detergent compound and a cationic mono-higher alkyl quaternary ammonium compound fabric softening agent is significantly enhanced by using the cationic softener as an approximately 1:1 complex with an anionic surfactant which is a linear alkyl aromatic sulfonate. This discovery is the subject matter of applicant's copending application Ser. No. 661,775, filed Oct. 17, 1984, the disclosure of which is incorporated herein by reference. Furthermore, this enhancement of the softening/anti-static performance was achieved without sacrificing, and in some cases, with significant improvement in the whitening and cleaning performance.
While excellent softening and anti-static benefits have been provided by the liquid nonionic detergent compositions based on the complex of the cationic fabric softener and linear alkyl benzene sulfonate, the present inventor has also previously discovered that further improvements in overall cleaning performance and the ability to form complexes of the mono-higher alkyl quaternary fabric softener with a broader range of commercially available anionic detergents can both be attained by adding to the composition an additional surfactant compound which is a sulfosuccinamate compound. This discovery is the subject matter of applicant's copending Ser. No. 873,486, filed Jun. 12, 1986, now U.S. Pat. No. 4,790,856 the disclosure of which is incorporated herein by reference. The incorporation of the sulfosuccinamate compound significantly boosts detergency of the nonionic/cationic mixture with or without the additional benefits of other anionic surfactants.
The use of polyethylene terephthalate-polyoxyethylene terephthalate (PET-POET) soil release promoting polymers is well documented in the patent literature. Representative examples of the patent literature disclosing the use of PET-POET and similar polymers in the treatment of synthetic textile materials, in general, and in laundry detergent compositions, in particular, include, among others, U.S. Pat. No. 3,557,039 (and its corresponding British Patent Specification 1,088,984); U.S. Pat. Nos. 3,652,713; 3,723,568; 3,959,230; 3,962,152; 4,125,370; 4,132,680; 4,569,772; and British Patent Specifications 1,154,370; 1,317,278; 1,377,092; and British Published Patent application 2,123,848 A.
U.S. Pat. No. 3,557,039 to McIntyre et al. shows the preparation of such copolymers by the ester interchange and subsequent polymerization of dimethyl terephthalate (DMT) and ethylene glycol (EG) in the presence of a mixed catalyst system of calcium acetate hemihydrate and antimony trioxide. A similar reaction is shown in U.S. Pat. No. 3,959,280 to Hays, this patent further using polyethylene oxide as one reactant in addition to DMT and EG monomers. The PET-POET copolymers of Hays are characterized by a molar ratio of ethylene terephthalate units to polyethylene oxide terephthalate units of from about 25:75 to about 35:65, by the polyethylene oxide of the polyethylene oxide terephthalate having a molecular weight of from about 300 to 700, by a molecular weight of about 25,000 to about 55,000, and by a melting point below 100.degree. C.
U.S. Pat. No. 3,652,713 forms antistatic fibers, films and other shaped articles from compositions in which polyethylene terephthalate is mixed with a polyether-polyester block copolymer such that the polyether segment constitutes from 0.1 to 10.0% by weight based on the total weight of the mixture. The polyether-polyester block copolymer can be prepared by melt-polymerizing (condensation polymerization) polyethylene terephthalate of number average molecular weight of from 1,000 to 2,000 with polyethylene glycol having a number average molecular weight of from 1,000 to 50,000 at a highly reduced pressure and elevated temperature in the presence of antimony trioxide and trimethyl phosphate.
According to British 1,317,278 to Ambler et al. high molecular weight (e.g., spinning-grade or film-forming) polyethylene terephthalate is reacted with polyethylene glycol (MW=300 to 30,000) at temperatures in the range of 100.degree. C. to 300.degree. C., preferably at atmospheric pressure in the presence of conventional ester exchange catalyst, for example, antimony oxides, calcium acetate, tetralkyltitanates and stannous octoate.
U.S. Pat. No. 4,125,370 to Nicol discloses PET-POET soil release promoting random copolymers having an average molecular weight in the range of about 5,000 to about 200,000, with a molar ratio of ethylene terephthalate to polyethylene oxide terephthalate of from about 20:80 to 90:10, the polyethylene oxide linking unit having a molecular weight in the range from about 300 to 10,000. These polymers can be prepared according to the procedure disclosed in the aforementioned U.S. Pat. No. 3,959,280 to Hays or by the process described in U.S. Pat. No. 3,479,212 to Robertson et al.
PET-POET soil release promoting polymers are also commercially available, for example, the products Alkaril QCJ and QCF from Alkaril Chemicals, Inc.; Milease T from ICI America; and Zelcon from E. I. duPont de Nemours & Co.
While satisfactory soil release promoting property has been obtained from the commercially available products and as described in the literature, there have been problems with regard to the stability, as well as effectiveness, of these copolymers during storage and under actual use conditions. Thus, U.S. Pat. No. 4,125,370 teaches providing a concentration of certain hardness ions to promote deposition of the soil release polymers on the fabrics being washed and to promote soil release performance. U.S. Pat. No. 4,569,772 teaches that detergent compositions containing PET-POET polymers tend to lose their soil release promoting properties on storage, if the compositions contain alkaline builders. The patentees overcome this tendency by co-melting the PET-POET copolymer with a water-soluble alkali metal polyacrylate and converting the melt to solid particles. British Published Patent application 2,123,848 A overcomes this tendency by uniformly distributing the PET-POET copolymer throughout the particulate detergent product by preparing particles of a builder or a mixture of builders for a non-ionic detergent, dissolving and/or dispersing in such non-ionic detergent in liquid state a substantially anhydrous soil release promoting PET-POET polymer, and spraying such liquid non-ionic detergent-polymer mixture onto moving surfaces of the builder particles to distribute such non-ionic detergent and polymer over such particles.
While excellent softening and anti-static benefits have been provided by the liquid non-ionic detergent compositions based on the complex of the cationic fabric softener and anionic detergents such as linear alkyl benzene sulfonate, and while stable compositions of PET-POET polymers with non-ionic detergents have been achieved, there still exists a problem of incompatibility when formulating liquid detergents containing both cationic fabric softeners and commercially available PET-POET soil release promoting copolymers. In particular when a commercially available PET-POET soil release promoting copolymer, such as Alkaril QCJ, is added to a liquid detergent containing a non-ionic surfactant and an anionic surfactant, the liquid is slightly turbid, but the suspension is stable over time. When a cationic fabric softener is added to this liquid, the suspension becomes unstable, and a fine precipitate settles out over a period of time. This fine precipitate considerably degrades the appearance of the product to the consumer, especially when packaged in translucent containers and subjected to long-term storage prior to sale.